Method of coating pipe



May 24, w49, R. c. s'rRoMQuls-r METHOD 0F COATING FIRES 2 Sheets-Sheet 1Filed oct. 25. 1945 ATTORNEYS 2 Sheets-Sheet 2 R. C. STROMQUIST Ammon oFcomme IrEs rl lll.:

May 24, L1949.

Filed oct. 25. 1945 Patented May 24, 1949 l Russell C. Stromquist,Westfield, N. J., assignor, by mesne assignments, to Koppers Company,

Inc.,

a corporation of Delaware Application October 25, 1945, Serial No.624,458

l This invention relates toa method of coating metal pipe with hotliquid bitumen, and in particular to coating the interior of such pipeto protect the metal of the pipe from the corrosive action of fluidspassing through them. As the bitumen hardens well above atmospherictemperatures, it is applied hot and in liquid condition. As hot liquidbitumen will not adhere to cold metal surfaces, two methods have beenemployed to effect adhesion: (l) a priming coat is first applied anddried, or (2) the entire pipe is heated before the coating is-applied.Both of these are time-consuming and expensive. According to the presentinvention I subject the surface to be coated to an intense heatimmediately prior to or simultaneously with the application of the hotliquid bitumen. The intensity and duration of the heat vare correlatedso as to raise uniformly the skin of the pipe to be coated momentarilyto a temperature high enough to ensure the necessary bond .between themetal and the bitumen without, however, appreciably raising thetemperature of the body of the pipe underlying the heated skin. I thusavoid the need for applying a primary coat' or preheating the entirepipe.

My method has another advantage. The` oxy-` acetylene iiame, which Iprefer to use as my source of heat, acts to cleanse the surface of thepipe. Any large pieces of scale dislodged would have to `be removed, asby blowing, but small pieces would simply be imbedded in the bitumen anddo no harm.

In using my method to coat the interior of a pipe, I rotate the pipe,then move through it a heater in the form of a flame head whichprogressively applies heat locally, and preferably follow it witl1`avalved nozzle through the orifice of which hot liquid bitumen isprogressively discharged upon the heated areas. The dame head is connedbetween two circular oaiiies which travel with it and, by coniining andconcentrating the heat within a limited section of the pipe at any givenmoment, increase the speed at which the pipe surface is heated.Auxiliary air for combustion is supplied to the space between thebaiiles.

In the accompanying drawings I have illustrated a form of apparatuswhich I have suc-l cessfully used in carrying out my method, and whichapparatus forms the subject matter of my copending application, SerialNo. 624,459, filed October 25, 1945.

In these drawings:

Figure 1 is a side elevation of the entire appa- 2 Claims. (Cl. 117-49)CFI gflame head and their Within the pipe,

2 ratus showing the, pipe to be coated, mounted for rotation at theleft-hand end of the apparatus, with the flame head and bitumen nozzleretracted and their connections to the various sources of supply shown,i

Figure 2 is a transverse section taken along line 2-2 of Figure l,

Figure 3 is a transverse section taken along line 3-3 of Figure 1,

Figure 4 is a Vertical, longitudinal section, on an enlarged scalethrough a pipe to be coated, showing in elevation the bitumen nozzle,the connections supported Figure 5 is a horizontal, longitudinal sectionthrough the pipe showing the parts shown in Figure 4 in plan, and fAFigure 6 is a vertical transverse section taken along line 6-6 ofFigure 4.

rIThe apparatus shown in these drawings is supported on a long trestleI, comprising a pair o channel irons 2 supported on uprights 3 and tiedtogether by cross pieces 4. A pair of rails 5 mounted on the channelirons 2 form a track on which a carriage 6 is mounted and driven ineither direction by means of a motor 1 through driving connections 8comprising clutch, chains and sprockets. On this carriage are mountedal1 of the movable parts of the apparatus which I shall describepresently.

Mounted upon upright frames 9 at the lefthand end of the trestle are twopairs of rollers I Il journaled in bearing plates II and rotatablysupporting the pipe I2 to be coated. One or more of these rollers isconnected to a power drive, not shown.

Mounted on the carriage 6 is a supply kettle I3 containing the hotliquid bitumen which is kept in molten condition by means of the usualoil yburner I4 supplied from a tank I5 likewise mounted on the carriage.The bitumen is heated to the application temperature in larger kettles,not shown, which are located alongside the apparatus, and transferred tothe smallel` supply kettle I3, as needed. Mounted on the carriage infront of the kettle is a pump I6 driven by a motor I1. This pumpwithdraws liquid bitumen from the kettle through section I8, and passes`it through sections I9, 20 and 2| to a long horizontal conduit 22carrying at its outer end a modified three-way valve 23 .provided with anozzle 24 having a discharge orifice 25.` Connected to the far sideofvalve 23 is a return conduit 26 which through sections 21, 28, 29 and 3|returns any unused bitumen to the kettle.

Lying between the conduits 22 and 2l adjacent the valve 23 is a flamecleaning head 22, the flame outlets of which point toward the lower,inner face of the pipe and are closely adjacent to it, as shown inFigure 4. A mixture of oxygen and acetylene is fed to this flame head bya duct 33 from a mixing chamber 34 to winch the gases are fed throughflexible tubes Il and 36 leading from oxygen and acetylene cylinders l1and Il respectively. The flame head 82 is confined between two circularbafiies I9 and 40 which substantially fill the pipe and provide anenclosed space for the flame head to operate in. The bitumen conduits 22and 26 pass through these bailles and are secured thereto while a slot4i in baille 39 provides for the passage of the oxyacetylene duct 33.Auxiliary compressed air for combustion is delivered to the spacebetween the bailles 39 and 40 through a duct 42 surrounding andconcentric with duct 33. which duct likewise passes through slot 4i.This duct 42 is connected to a source of compressed air, not shown,through flexible hose 43.

The bitumen conduits and valve, and the flame head and connections aresupported by means of rollers 44 journaled between pairs of plates 4l.As in the case of the bailles 39 and 40, the bitumen conduits passthroughand are secured to these plates 45 while the oxyacetylene duct 3land the auxiliary air duct 42 pass through slots 46 therein. During thecoating operation, the bitumen nozzle and name head and their variousconnections are supported by the rollers 44 upon the pipe itself.Supported upon the trestle in alignment with and closely approaching theinner end of the pipe I2 is a channel 41 which supports these'parts whenin their retracted or partly retracted position. It will be understoodthat a plurality of sets of rollers 44 are provided so that amplesupport is provided at spaced intervals.

The apparatus operates as follows: The pipe to be coated is placedhorizontally upon the rollers l0, whereupon the carriage is moved to theleft (referring to Figure i) until the valve 23 and the flame head havepassed through the pipe and project beyond it on the far side. The

motor I6 is started to circulate bitument from the kettle through thepiping, previously described, and back to the kettle, whereupon theflame is ignited and the valve opened to permit the discharge of hotliquid bitument through the orifice 25 of the nozzle 24. The pipe isthen rotated and the carriage moved to the right by means of motor 1 anddrive l so that the flame head, and immediately following it the streamof bitumen discharged from the nozzle orifice, move progressively alongthe length of the rotating pipe. When the flame head and valve havepassed through the pipe to the position, shown in Figure 1, the movementof the carriage is arrested, the flame is shut of! and the valve closed.Circulation ofthe bitumen continues after the closing of the valve sothat there is no danger of its freezing in the conduits between coatingoperations.

By using one 6" flame cleaning head it is possible to coat the interiorsurfaces of pipes at a rate of approximately 1050 square feet per hour,with a consumption of oxygen and acetylene gases of approximately 137cubic feet per hour for each gas. Auxiliary compressed air is s uppliedat the rate of approximately 900 cubic feet per hour. If it is desiredto coat pipes ata rate greater than 1050 square feet per hour.additionalV name cleaning heads may be added to this mechanism; thus therate at which the pipe can be coated will be increased by the number offlame cleaning heads used and will be in a direct ratio to the quantityof oxygen and acetylene gases consumed per hour based on an approximatecoating rate of 1050 square vfeet per hour 137 cubic feet of oxygen and137 cubic feet of acetylene gases consumed per hour. The diameter of thepipe and the rate at which the pipe is desired to be coated will governthe number of flame cleaning heads to be used.'

The temperature to which the interior skin of the pipe must be heated inorder to effect a satisfactory bond between the metal and the bitumenwill vary depending upon` the nature of the bitumen used. Thetemperature required to effect a bond between the pipe and theconventional coatings used for lining pipe must be somewhat in excess of200 F. This temperature applies to a coal-tar coating conforming to A.W. W. A. Specifications 7A.51940 and 'IAG-1940 for Coal Tar ProtectiveCoatings for Steel Water Pipe.

The oxyacetylena flame is a high temperature flame which can develop alocal temperature of at least 2000 F. and so cleanse the surface of thepipe of scale and dirt. The rate of movement of the flame-cleaning headis such that the pipe is neither burned nor overheated, but is such thatthe surface temperature of the pipe will be somewhat in excess of 200 F.when .the molten bitumen is applied to the surface from the nozzle.

I claim:

1. In the method of obtaining a substantially continuous uniform coatingof bitumen of a metal pipe of substantial length :by first applying heatto the pipe and subsequently applying the bitumen in a melted state; theimprovement which comprises applying intense local heat successively toportions of the surface of the pipe to be coated, the intensity andduration of the heat applied to such successive portions beingcorrelated so as to raise uniformly the skin only of the successiveportions 0f the pipe to a temperature at which bitumen will adherewithout appreciably raising the temperature of the body of the pipe wallunderlying the heated skin, causing relative motion between the sourceof heat and the pipe in a direction longitudinally of the pipe andsimultaneously applying the hot melted bitumen to the successivelyheated portions of the pipe immediately after the application of theheat thereto and While the successive portions of the pipe are at suchtemperature.

2. In the method of obtaining a substantially continuous uniform coatingof bitumen on the interior of a metal pipe of substantial length byfirst applying heat to the pipe and subsequently applying the .bitumenin a melted state; the improvement which comprises rotating the pipe,

simultaneously with the rotation of the pipe applying intense local heatsuccessively to portions of the interior surface of the pipe to becoated, the intensity and duration of the heat applied to suchsuccessive portions being correlated so as to raise uniformly the skinonly of the successive portions of the pipe to a, temperature at whichbitumen will adhere without appre-` ciably raising the temperature ofthe body of the pipe wall underlying the heated skin, `causing relativemotion between the source of heat and the pipe in a directionlongitudinally of the pipe and simultaneously applying the hot meltedbitumen to the successively heated portions of the pipe immediatelyafter the application of the heat thereto and while said successiveportions of the pipe are at such temperature. Y

RUSSELL C. STROMQUIST.

REFERENCES CITED The following references are of record in the le ofvthis patent:

Number Wissler Sept. 15, 1942

